Comparison between Ammonia+CO2 integrated refrigeration system and Glacier Coolant refrigeration system

1. Safety

Ammonia as primary refrigerant is toxic, flammable and explosive. CO₂ which is the secondary refrigerant operates at pressure five times higher than Glacier Coolant. The Glacier coolant secondary refrigeration system runs at almost ambient pressure and the pump is only designed for overcoming system hydraulic loss.

Due to the characteristics of ammonia, the project can be identified as high hazardous project and requires frequent round checks. The pipework of CO₂ needs to be designed to withstand high pressure (GC2 grade) and be closely monored as well. Glacier Coolant refrigeration system is not required to comply with such regulations due to its safe characteristics.

2.    Cost

The equipment cost of ammonia+CO₂ refrigeration system is 10% higher than that of Glacier Coolant refrigeration system. Ammonia and CO₂ system requires dedicated compressor. For CO₂ system, higher pressure head is required than that of ammonia or Freon compressor. Subsequently, higher pressure grading is required for its auxiliary systems such as pipes and valves.

As Glacier Coolant refrigeration systems operates at much lower pressure, it saves significant equipment cost. Standard pipes and valves can be selected. Apart from equipment cost, ammonia system also requires safety measures of  fencing wall and impoundment. The coexisting of ammonia and CO₂ systems requires dedicated ventilation systems due to their different density, adding further cost of ammonia+CO₂ refrigeration system.

3.    Operation conditions

Phase transition take place in both ammonia and CO₂ refrigeration systems at uncontrolled rate resulting in temperature fluctuation. It requires more complicated process control system and instrumentation, which further increases cost. Intensive training of labor is also required.

If there is a fire incident, both ammonia and CO₂ need to be discharged in a safe way. Regular training is pivotal and mandatory. The system cannot be shut down for long period of time otherwise the pressure of CO₂ will continue to increase in the system. It is also not energy efficient to run CO₂ system at low demand of cooling.

The Glacier Coolant refrigeration system works together with primary refrigerant of Freon and it utilizes sensible heat. It stabilizes the system and the automation is simple. The temperature of coolant is controlled by varying flow rate which is driven by the compressor. Under emergency situation, Glacier Coolant can be remained in the system as long as needed, without concerns of over- pressurization, even during long term shut down.